Ischemic stroke is a highly heterogeneous clinical condition resulting from an obstruction in cerebral blood flow due to thrombotic and/or embolic vascular occlusion. A key priority in the treatment of any such disturbance is to rapidly re-establish the supply of essential metabolic substrates to the affected neural tissue. This is the rationale behind fibrinolytic (clot-lysis) therapy, which facilitates the recanalization of occluded vessels, thus improving neurological outcome. It is currently the only FDA-approved drug-based therapy for the treatment of acute ischemic stroke;however, its utility is dramatically constrained by a relatively brief window of therapeutic opportunity, partial or incomplete recanalization of occluded vessels, slow recanalization of vessels, and the potential to exacerbate injury in hemorrhagic strokes. An alternative, yet complementary, approach to reestablishing metabolic competency is to facilitate the delivery of essential metabolites to the ischemic tissue. This proposal will define and characterize the utility of a therapeutic approach, termed "metabolic reflow", in which the delivery of metabolic substrates is enhanced to protect ischemic tissue. Trans-sodium crocetinate (TSC) is a novel carotenoid compound that increases the diffusivity in plasma of small molecules, including oxygen and glucose. This compound has been shown to improve oxygen delivery to a variety of tissues, including the brain parenchyma. Our preliminary studies provide the first evidence that TSC enhances oxygenation of ischemic brain tissue, exerts a potent and highly significant protective effect against cerebral injury in experimental models of both temporary and permanent ischemia, and is protective even when administered on a delayed basis. The central goal of this application is to define the protective effects of TSC in the context of ischemic stroke. The studies will examine the hypothesis that metabolic reflow is the mechanism underlying cerebral protection by TSC. The studies will identify the therapeutic window for TSC treatment, determine its optimal therapeutic dosage range, establish whether TSC is capable of extending the therapeutic window for reperfusion (clot-lysis) therapy, and define the influence of TSC on hemorrhagic stroke. Together these studies will provide key evidence for defining the mechanism(s) and utility of TSC- induced cerebral protection as a novel therapeutic candidate for early intervention in stroke. PUBLIC HEALTH RELEVANCE: This research project will study the efficacy of a new candidate therapy for treating stroke. Stroke is the third most common cause of death and the number one cause of disability in the United States. A primary cause of injury in stroke is a reduction in blood flow to the brain. This results in a loss of metabolic supply (i.e. loss of oxygen and glucose supply) to the nerve cells and ultimately leads to their death. The new candidate therapy, termed metabolic reflow will use a drug called trans-sodium crocetinate to reinstate the metabolic supply to the brain and protect against the loss of nerve cells. The overall goal of the studies is to test whether this novel therapeutic approach is effective in protecting the brain during stroke.